1. Field of the Invention
The present invention relates to a substrate transfer method and a substrate processing apparatus.
2. Description of the Related Art
In order to efficiently perform a semiconductor manufacturing process, a substrate processing apparatus that has a cluster structure provided with a plurality of processing chambers is provided. In such a substrate processing apparatus, a plurality of substrates are transferred to the plurality of processing chambers, and the plurality of substrates are processed in the plurality of processing chambers, respectively, in parallel.
When different processes are performed in the plurality of processing chambers, process times may be different. In such a case, timings for carrying substrates into/out from the plurality of processing chambers may overlap. Thus, there may be a case that, when a preceding substrate is being carried into/out from one of the processing chambers, carrying of a substrate into/out from another one of the processing chambers is suspended. In order to shorten this waiting time, it can be considered to provide a buffer portion, on which a substrate to be processed next is mounted, in a vacuum state transfer chamber. However, as it is necessary to carry the substrate into/out from the buffer portion by an arm under a vacuum state, additional transferring time is necessary and there may be a case that carrying of another substrate into/out from another processing chamber is suspended.
Thus, Patent Document 1 discloses a substrate processing apparatus capable of carrying a plurality of substrates into/out from a load lock chamber by providing a buffer portion, on which the plurality of substrates are capable of being mounted, in the load lock chamber.
However, the volume of the load lock chamber increases by providing the buffer portion therein. Thus, evacuating time for changing the pressure of the load lock chamber between an atmospheric pressure and a vacuum pressure increases. Because of this, the maximum value of a mechanical throughput for the substrate processing apparatus as a system is lowered.
In order to solve this problem, a method of rapidly vacuuming the load lock chamber or exposing the load lock chamber to the atmosphere is considered, however, in such a case, there is another problem such as flinging up of particles, condensation or the like occurs.
Further, a case may be considered in which two load lock chambers, one of which is capable of transferring a plurality of substrates and the other of which is capable of transferring a single substrate, are provided, and one of them is selected in accordance with process statuses of the substrates. However, in such a case, footprint increases.